GMAT Math : Calculating percents

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #1 : Percents

330 is what percent of 11?

Possible Answers:

\dpi{100} \small 3\%

\dpi{100} \small 3000\%

\dpi{100} \small 33\%

\dpi{100} \small 30\%

\dpi{100} \small 300\%

Correct answer:

\dpi{100} \small 3000\%

Explanation:

This problem can be solved by the equation: 330 = 11x, where \dpi{100} \small x is the answer in terms of a percentage. To solve for \dpi{100} \small x both sides are divided by \dpi{100} \small 11: \frac{330 }{11}= x. This can be simplified to: 30 = x. Now \dpi{100} \small 30 is converted to a percentage to find the answer.

\dpi{100} \small 30 as a percentage is \dpi{100} \small 3000\%

Example Question #2 : Percents

Three years ago, Anum invested $25,000 in a new mutual fund account. The value of the account increased by 15% during the first year, increased by 7% during the second year, and decreased by 15% during the third year. What is the approximate value of the account today?

Possible Answers:

\dpi{100} \small \$ 35,000

\dpi{100} \small \$ 27,000

\dpi{100} \small \$ 26,000

\dpi{100} \small \$ 25,000

\dpi{100} \small \$ 31,000

Correct answer:

\dpi{100} \small \$ 26,000

Explanation:

The first year increase of 15% can be represented as 1.15; the second year increase of 7% can be represented as 1.07; and the third year decrease of 15% can be represented as 0.85.

Multiply the original investment by each annual change.

25,000(1.15)(1.07)(0.85) = 26,148

approx. $26,000

Example Question #2 : Percents

Max the cat has 70 toy mice. If 30% of the mice are new, how many mice are not new?

Possible Answers:

40

30

60

21

49

Correct answer:

49

Explanation:

If 30% of the mice are new, then 70% are not new.

\dpi{100} \small 0.7\times 70=49

Example Question #4 : Percents

37% of the greatest common factor of 50 and 350 is

Possible Answers:

Correct answer:

Explanation:

The greatest common factor of 50 and 350 is simply 50.  Now we must take 37% of 50. 

.

Example Question #5 : Percents

A shirt costs $60. The price was then increased by 30%. What is the new price as expressed in terms of the original price?

Possible Answers:

Correct answer:

Explanation:

Example Question #6 : Percents

A GMAT score increases from 450 to 540. By what percent did the score increase?

Possible Answers:

Correct answer:

Explanation:

Example Question #7 : Percents

Out of 60 students, 15 prefer to study at night. What percent of students prefer nighttime studying?

Possible Answers:

25%

60%

15%

4%

Correct answer:

25%

Explanation:

Cross multiply

Divide both sides by 60

Example Question #8 : Percents

Geri earns a commission of 22.5% on everything she sells for KM Cosmetics. As of the fifteenth of the month, she has sold $2,100 worth of cosmetics. How much more in cosmetics must she sell in order to earn at least $900 commission for the month?

Possible Answers:

She has already sold enough to earn $900 commission.

Correct answer:

Explanation:

Commission can be calculated by muliplying the commission rate - 22.5%, or 0.225 - by the amount of sales, so the amount of sales needed can be found by dividing the desired commission by 0.225.

Since Geri has already sold $2,100 worth of cosmetics, she needs to sell  more.

Example Question #1 : Percents

A number is multiplied by six; then its decimal point is moved to the left three spaces. This is the same as taking what percent of the number?

Possible Answers:

 %

 %

 %

 %

 %

Correct answer:

 %

Explanation:

Let's do these two things to 100. Multiplying 100 by 6 yields 600; moving the decimal point three places left changes 600, or 600.0, to 0.60.

This means that the new number is 0.60% , or  %, of the original number.

Example Question #10 : Percents

A number is divided by two; then its decimal point is moved to the left two spaces. This is the same as taking what percent of the number?

Possible Answers:

 %

 %

 %

 %

 %

Correct answer:

 %

Explanation:

Let's do these two things to 100. Dividing 100 by 2 yields 50; moving the decimal point two places left changes 50, or 50.0, to 0.50.

This means that the new number is 0.50% , or  %, of the original number.

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